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Atmospheric battle will determine where Dorian hits Florida

Published Thu Aug 29 2019 20:47:24 GMT+0000 (UTC)

by BY SETH BORENSTEIN

It's a battle of mammoth meteorological forces, and at stake is where Hurricane Dorian strikes the United States.

Four days before the system is expected to come ashore, Dorian could hit practically anywhere in Florida because the weather forces that will determine its path have not yet had their showdown, meteorologists said. As of Thursday, the National Hurricane Center had practically all of eastern Florida in a cone of uncertainty, meaning the entire region was at risk.

Forecasters are fairly confident about one thing: Dorian will be powerful.

With 86-degree water as fuel and favorable moist winds, there's little to prevent the storm from powering up Friday. On top of that, the warmer-than-normal water is running deeper than usual, adding more fuel. The hurricane center predicts Dorian will make landfall on Labor Day as a Category 4 storm with 130 mph winds.

Stacy Stewart, a senior hurricane specialist at the center, said there's a chance for a "fairly dramatic" change in storm direction on Saturday based on what's happening in the atmosphere and the storm altering its own environment, helping to steer its own path.

The forces that will determine Dorian's fate — and that of Florida — are already at work.

A high pressure system is building over Bermuda, acting as a wall and blocking storms from curving north, which is a natural pathway. It is essentially pushing Dorian westward, more toward densely populated southern Florida, said University of Miami hurricane researcher Brian McNoldy.

Meanwhile, a low pressure system in the Midwest is chugging eastward. When it clashes with the Bermuda high, there's a chance it will nibble away at the western edges, allowing a weakening in that wall and pulling Dorian to the northwest toward Cape Canaveral or Jacksonville, with a small chance of the storm heading north of Florida, said Weather Underground Meteorology Director Jeff Masters, who used to fly into hurricanes for forecasts.

Whichever one of those forces wins — the blocking high or the pulling low — Florida is likely to lose.

Dorian will have a lot to say about its own movements. Stewart said the storm can feed back on its surroundings and modify them, effectively allowing the hurricane to chart its own course.

Stewart sees the high pressure system winning, with an assist from Dorian itself. That means following a track that points generally toward Palm Beach County and President Donald Trump's Mar-a-Lago resort.

Colorado State hurricane researcher Phil Klotzbach said the slower the storm moves, the more time there is for the atmospheric wall to weaken and Dorian to be pulled farther north. That's why Klotzbach sees similarities between Dorian and 2004's Frances , which hit Stuart, Florida, with 105 mph winds and caused nearly $9 billion in damage in the United States.

So far, Dorian is a relatively small storm. Because of that "a small change in track can make big differences in terms of where it ends up," Klotzbach said.

A slower speed also means Dorian can dump more rain and bring more opportunities for storm surges to hit during high tide. And a new moon means extra high tides, Masters said.

"If it makes landfall as a Category 3 or 4 hurricane, that's a big deal," McNoldy said. "A lot of people are going to be affected. A lot of insurance claims. It's still quite an ordeal."

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.

This Thursday, Aug. 29, 2019 image provided by NASA shows a view of Hurricane Dorian from the International Space Station as it churned over the Atlantic Ocean north of Puerto Rico. Leaving mercifully little damage in its wake in Puerto Rico and the Virgin Islands, Hurricane Dorian swirled toward the U.S., with forecasters warning it will draw energy from the warm, open waters as it closes in. (NASA via AP)This GOES-16 satellite image taken Thursday, Aug. 29, 2019, at 14:20 UTC and provided by National Oceanic and Atmospheric Administration (NOAA), shows Hurricane Dorian, right, moving over open waters of the Atlantic Ocean. The U.S. National Hurricane Center said Dorian was expected to grow into a potentially devastating Category 3 hurricane before hitting the U.S. mainland late Sunday or early Monday somewhere between the Florida Keys and southern Georgia. (NOAA via AP)Map shows Hurricane Dorian's projected path; 3c x 3 inches; 146 mm x 76 mm;